$$\text{ATP} \rightarrow \text{cAMP} + \text{PP}_i$$

Question 1

Which of the following best explains why lipid-soluble hormones require transport proteins in the bloodstream?

Accepted Answer

They are hydrophobic and would not dissolve well in the water-based blood plasma without transport proteins.

Question 2

A patient with chronically high levels of insulin develops resistance to its effects. Which cellular process is most likely responsible?

Accepted Answer

Down-regulation of insulin receptors on target cells.

Question 3

Which hormone interaction is demonstrated when two hormones, such as LH and FSH, work together to amplify their effects on the gonads?

Accepted Answer

Synergistic

Question 4

During a stressful event, sympathetic nerve fibers stimulate the adrenal medulla. Which hormone is released and what is its immediate effect?

Accepted Answer

Epinephrine; increases heart rate and blood glucose

Question 5

Which of the following best describes the mechanism of action for water-soluble hormones?

Accepted Answer

They bind to surface receptors and activate second messenger systems such as cAMP.

Question 6

A patient presents with low blood calcium. Which hormone is released, and what is its primary action?

Accepted Answer

Parathyroid Hormone (PTH); stimulates osteoclasts to increase blood calcium

Question 7

Which of the following equations correctly represents the conversion catalyzed by adenylate cyclase in the cAMP second messenger pathway?

Accepted Answer

$$	ext{ATP} ightarrow 	ext{cAMP} + 	ext{PP}_i$$

Question 8

Which hormone is released in response to a humoral stimulus, such as declining blood calcium levels?

Accepted Answer

Parathyroid Hormone (PTH)

Question 9

A patient with a thyroid disorder is found to have insufficient dietary iodide. Which hormone synthesis is most directly affected?

Accepted Answer

Thyroid hormones (T3 and T4)

Question 10

Which of the following best describes the anatomical relationship between the hypothalamus and the pituitary gland?

Accepted Answer

The hypothalamus is in the diencephalon and attached to the pituitary by the infundibulum.

Question 11

Which hormone operates via a positive feedback loop to drive uterine contractions during labor?

Accepted Answer

Oxytocin

Question 12

Which of the following is a correct sequence for the hypothalamic-pituitary-thyroid axis when thyroid hormone levels are low?

Accepted Answer

Hypothalamus releases TRH, anterior pituitary releases TSH, thyroid releases T3 and T4.

Question 13

Which of the following best describes the function of protein kinases in the cAMP signaling pathway?

Accepted Answer

They phosphorylate other proteins, activating or deactivating them to trigger a cellular response.

Question 14

Which hormone is secreted by pancreatic beta cells and what is its effect?

Accepted Answer

Insulin; decreases blood glucose by promoting glycogenesis and lipogenesis.

Question 15

Which of the following is a correct description of the adrenal cortex zones and their primary hormones, from outermost to innermost?

Accepted Answer

Zona Glomerulosa (mineralocorticoids/aldosterone), Zona Fasciculata (glucocorticoids/cortisol), Zona Reticularis (androgens/sex steroids)

Question 16

Which hormone is released in response to low blood glucose and what are its two main metabolic effects?

Accepted Answer

Glucagon; stimulates glycogenolysis and gluconeogenesis

Question 17

Which of the following best describes the difference between negative and positive feedback mechanisms in endocrine regulation?

Accepted Answer

Positive feedback amplifies a deviation until a definitive endpoint is achieved, whereas negative feedback stabilizes a variable near a setpoint.

Question 18

Which hormone is produced by the pineal gland and how do its levels change during a typical 24-hour cycle?

Accepted Answer

Melatonin; levels decrease during the day and increase at night to promote sleep.

Question 19

A patient with chronic stress has elevated cortisol levels. What is a likely consequence of this hormonal imbalance?

Accepted Answer

Suppressed immune system and increased susceptibility to illness.

Endocrine System Practice Exam – Step-by-Step Study Guidance

Study Guide - Practice Questions